The present invention relates to electromechanical programmers or timers as they are sometimes called employed for controlling the cycle of operation or program for an electrically operated appliance. Programmers employed for household appliances such as washing machines, dish washers and clothes dryers typically have a plurality of appliance function switches sequentially operated during a selected program time interval by a rotating cam which is advanced during the program interval by a timing motor advance mechanism. In the more common arrangements of such programmers for household appliances, the programmer is mounted behind the panel; and, the appliance user selects the desired program interval by rotating a knob attached to the shaft for the cam extending through the panel to position the cam initially for providing the selected interval for timeout of the program. It is commonplace to have a dial knob attached to the cam shaft with indicia of a program on the console for user selection of the desired program and interval.
Heretofore, appliance programmers that are user positioned by a rotary knob or dial for selection of the desired program have also incorporated a line power switch actuated by axial movement of the dial knob and cam shaft. Typically, in such programmer arrangements an auxiliary cam is provided on the program cam shaft for actuation of a separate line power switch by the axial movement of the knob. However, a disadvantage of this arrangement has been that it has still been possible for the user to rotate the program cam and cause actuation of the program switches when the line power switch was closed. This rotation caused actuation of the machine function switches for switching current rapidly on and off to the appliance functions. Such rapid operation of the various machine functions by the user rotating the program cam rapidly with the line power switch closed has been found to be harmful to the various machine functions controlled by the program switches.
It has been proposed to provide an appliance programmer wherein the user selects the desired program interval by rotary positioning of a dial or knob for the program switch cam and also to provide a sequential push/push reset action to the knob shaft to require the user to reset the knob shaft to close the line power switch and to prevent the program cam from being rotated when the knob is rotated with the shaft in the nonreset mode. However, in order to provide such a combination of actuations for the appliance user control knob, it has been found difficult to combine these features in a single dial rotary cam electromechanical programmer and to provide the desired push/push reset action for combined control of the program function switches and the line power switch. It has thus been desired to provide a way or means to disengage the program cam from the knob shaft when the line power switch is closed and to require reset of the knob in order to engage the cam with the knob and simultaneously open the line power switch. It has further been desired to provide the aforesaid functions in a simple construction for an electromechanical programmer which is manufacturable at low cost in high volume production.